This study took location in Putih River that located on the western part of Merapi volcano. The river crosses the national road that connects Yogyakarta and Central Java Provinces. SIMLAR V.1.0 software was used to simulate debris flow phenomena. Rainfall data was processed using Nakayashu method to obtain discharge for simulations. Topographical data as initial condition was used DEM (Digital Elevation Model) obtained using LIDAR (Light Detection and Ranging) method with precision 20 x 20 from Sabo Research Center, Indonesia. Grain size of riverbed material was used from field. The simulations were conducted in three conditions, namely no sabo works, with sabo works in existing condition and modified dimension of sabo works.